/*-------------------------------------------------------------------------
*
* bufmgr.c
* buffer manager interface routines
*
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.71 2000/01/17 01:15:17 inoue Exp $
*
*-------------------------------------------------------------------------
*/
/*
*
* BufferAlloc() -- lookup a buffer in the buffer table. If
* it isn't there add it, but do not read it into memory.
* This is used when we are about to reinitialize the
* buffer so don't care what the current disk contents are.
* BufferAlloc() pins the new buffer in memory.
*
* ReadBuffer() -- same as BufferAlloc() but reads the data
* on a buffer cache miss.
*
* ReleaseBuffer() -- unpin the buffer
*
* WriteNoReleaseBuffer() -- mark the buffer contents as "dirty"
* but don't unpin. The disk IO is delayed until buffer
* replacement if WriteMode is BUFFER_LATE_WRITE.
*
* WriteBuffer() -- WriteNoReleaseBuffer() + ReleaseBuffer()
*
* FlushBuffer() -- as above but never delayed write.
*
* BufferSync() -- flush all dirty buffers in the buffer pool.
*
* InitBufferPool() -- Init the buffer module.
*
* See other files:
* freelist.c -- chooses victim for buffer replacement
* buf_table.c -- manages the buffer lookup table
*/
#include <sys/types.h>
#include <sys/file.h>
#include <math.h>
#include <signal.h>
#include "postgres.h"
#include "executor/execdebug.h"
#include "miscadmin.h"
#include "storage/s_lock.h"
#include "storage/smgr.h"
#include "utils/relcache.h"
extern SPINLOCK BufMgrLock;
extern long int ReadBufferCount;
extern long int ReadLocalBufferCount;
extern long int BufferHitCount;
extern long int LocalBufferHitCount;
extern long int BufferFlushCount;
extern long int LocalBufferFlushCount;
/*
* It's used to avoid disk writes for read-only transactions
* (i.e. when no one shared buffer was changed by transaction).
* We set it to true in WriteBuffer/WriteNoReleaseBuffer when
* marking shared buffer as dirty. We set it to false in xact.c
* after transaction is committed/aborted.
*/
bool SharedBufferChanged = false;
static int WriteMode = BUFFER_LATE_WRITE; /* Delayed write is
* default */
static void WaitIO(BufferDesc *buf, SPINLOCK spinlock);
static void StartBufferIO(BufferDesc *buf, bool forInput);
static void TerminateBufferIO(BufferDesc *buf);
static void ContinueBufferIO(BufferDesc *buf, bool forInput);
extern void InitBufferIO(void);
extern void AbortBufferIO(void);
/*
* Macro : BUFFER_IS_BROKEN
* Note that write error doesn't mean the buffer broken
*/
#define BUFFER_IS_BROKEN(buf) ((buf->flags & BM_IO_ERROR) && !(buf->flags & BM_DIRTY))
#ifndef HAS_TEST_AND_SET
static void SignalIO(BufferDesc *buf);
extern long *NWaitIOBackendP; /* defined in buf_init.c */
#endif /* HAS_TEST_AND_SET */
static Buffer ReadBufferWithBufferLock(Relation relation, BlockNumber blockNum,
bool bufferLockHeld);
static BufferDesc *BufferAlloc(Relation reln, BlockNumber blockNum,
bool *foundPtr, bool bufferLockHeld);
static int FlushBuffer(Buffer buffer, bool release);
static void BufferSync(void);
static int BufferReplace(BufferDesc *bufHdr, bool bufferLockHeld);
void PrintBufferDescs(void);
/* ---------------------------------------------------
* RelationGetBufferWithBuffer
* see if the given buffer is what we want
* if yes, we don't need to bother the buffer manager
* ---------------------------------------------------
*/
Buffer
RelationGetBufferWithBuffer(Relation relation,
BlockNumber blockNumber,
Buffer buffer)
{
BufferDesc *bufHdr;
if (BufferIsValid(buffer))
{
if (!BufferIsLocal(buffer))
{
LockRelId *lrelId = & relation->rd_lockInfo.lockRelId;
bufHdr = &BufferDescriptors[buffer - 1];
SpinAcquire(BufMgrLock);
if (bufHdr->tag.blockNum == blockNumber &&
bufHdr->tag.relId.relId == lrelId->relId &&
bufHdr->tag.relId.dbId == lrelId->dbId)
{
SpinRelease(BufMgrLock);
return buffer;
}
return ReadBufferWithBufferLock(relation, blockNumber, true);
}
else
{
bufHdr = &LocalBufferDescriptors[-buffer - 1];
if (bufHdr->tag.relId.relId == RelationGetRelid(relation) &&
bufHdr->tag.blockNum == blockNumber)
return buffer;
}
}
return ReadBuffer(relation, blockNumber);
}
/*
* ReadBuffer -- returns a buffer containing the requested
* block of the requested relation. If the blknum
* requested is P_NEW, extend the relation file and
* allocate a new block.
*
* Returns: the buffer number for the buffer containing
* the block read or NULL on an error.
*
* Assume when this function is called, that reln has been
* opened already.
*/
#undef ReadBuffer /* conflicts with macro when BUFMGR_DEBUG
* defined */
/*
* ReadBuffer
*
*/
Buffer
ReadBuffer(Relation reln, BlockNumber blockNum)
{
return ReadBufferWithBufferLock(reln, blockNum, false);
}
/*
* is_userbuffer
*
* XXX caller must have already acquired BufMgrLock
*/
#ifdef NOT_USED
static bool
is_userbuffer(Buffer buffer)
{
BufferDesc *buf = &BufferDescriptors[buffer - 1];
if (IsSystemRelationName(buf->sb_relname))
return false;
return true;
}
#endif
#ifdef NOT_USED
Buffer
ReadBuffer_Debug(char *file,
int line,
Relation reln,
BlockNumber blockNum)
{
Buffer buffer;
buffer = ReadBufferWithBufferLock(reln, blockNum, false);
if (ShowPinTrace && !BufferIsLocal(buffer) && is_userbuffer(buffer))
{
BufferDesc *buf = &BufferDescriptors[buffer - 1];
fprintf(stderr, "PIN(RD) %ld relname = %s, blockNum = %d, \
refcount = %ld, file: %s, line: %d\n",
buffer, buf->sb_relname, buf->tag.blockNum,
PrivateRefCount[buffer - 1], file, line);
}
return buffer;
}
#endif
/*
* ReadBufferWithBufferLock -- does the work of
* ReadBuffer() but with the possibility that
* the buffer lock has already been held. this
* is yet another effort to reduce the number of
* semops in the system.
*/
static Buffer
ReadBufferWithBufferLock(Relation reln,
BlockNumber blockNum,
bool bufferLockHeld)
{
BufferDesc *bufHdr;
int extend; /* extending the file by one block */
int status;
bool found;
bool isLocalBuf;
extend = (blockNum == P_NEW);
isLocalBuf = reln->rd_myxactonly;
if (isLocalBuf)
{
ReadLocalBufferCount++;
bufHdr = LocalBufferAlloc(reln, blockNum, &found);
if (found)
LocalBufferHitCount++;
}
else
{
ReadBufferCount++;
/*
* lookup the buffer. IO_IN_PROGRESS is set if the requested
* block is not currently in memory.
*/
bufHdr = BufferAlloc(reln, blockNum, &found, bufferLockHeld);
if (found)
BufferHitCount++;
}
if (!bufHdr)
return InvalidBuffer;
/* if it's already in the buffer pool, we're done */
if (found)
{
/*
* This happens when a bogus buffer was returned previously and is
* floating around in the buffer pool. A routine calling this
* would want this extended.
*/
if (extend)
{
/* new buffers are zero-filled */
MemSet((char *) MAKE_PTR(bufHdr->data), 0, BLCKSZ);
smgrextend(DEFAULT_SMGR, reln,
(char *) MAKE_PTR(bufHdr->data));
}
return BufferDescriptorGetBuffer(bufHdr);
}
/*
* if we have gotten to this point, the reln pointer must be ok and
* the relation file must be open.
*/
if (extend)
{
/* new buffers are zero-filled */
MemSet((char *) MAKE_PTR(bufHdr->data), 0, BLCKSZ);
status = smgrextend(DEFAULT_SMGR, reln,
(char *) MAKE_PTR(bufHdr->data));
}
else
{
status = smgrread(DEFAULT_SMGR, reln, blockNum,
(char *) MAKE_PTR(bufHdr->data));
}
if (isLocalBuf)
return BufferDescriptorGetBuffer(bufHdr);
/* lock buffer manager again to update IO IN PROGRESS */
SpinAcquire(BufMgrLock);
if (status == SM_FAIL)
{
/* IO Failed. cleanup the data structures and go home */
if (!BufTableDelete(bufHdr))
{
SpinRelease(BufMgrLock);
elog(FATAL, "BufRead: buffer table broken after IO error\n");
}
/* remember that BufferAlloc() pinned the buffer */
UnpinBuffer(bufHdr);
/*
* Have to reset the flag so that anyone waiting for the buffer
* can tell that the contents are invalid.
*/
bufHdr->flags |= BM_IO_ERROR;
bufHdr->flags &= ~BM_IO_IN_PROGRESS;
}
else
{
/* IO Succeeded. clear the flags, finish buffer update */
bufHdr->flags &= ~(BM_IO_ERROR | BM_IO_IN_PROGRESS);
}
/* If anyone was waiting for IO to complete, wake them up now */
TerminateBufferIO(bufHdr);
SpinRelease(BufMgrLock);
if (status == SM_FAIL)
return InvalidBuffer;
return BufferDescriptorGetBuffer(bufHdr);
}
/*
* BufferAlloc -- Get a buffer from the buffer pool but dont
* read it.
*
* Returns: descriptor for buffer
*
* When this routine returns, the BufMgrLock is guaranteed NOT be held.
*/
static BufferDesc *
BufferAlloc(Relation reln,
BlockNumber blockNum,
bool *foundPtr,
bool bufferLockHeld)
{
BufferDesc *buf,
*buf2;
BufferTag newTag; /* identity of requested block */
bool inProgress; /* buffer undergoing IO */
bool newblock = FALSE;
/* create a new tag so we can lookup the buffer */
/* assume that the relation is already open */
if (blockNum == P_NEW)
{
newblock = TRUE;
blockNum = smgrnblocks(DEFAULT_SMGR, reln);
}
INIT_BUFFERTAG(&newTag, reln, blockNum);
if (!bufferLockHeld)
SpinAcquire(BufMgrLock);
/* see if the block is in the buffer pool already */
buf = BufTableLookup(&newTag);
if (buf != NULL)
{
/*
* Found it. Now, (a) pin the buffer so no one steals it from the
* buffer pool, (b) check IO_IN_PROGRESS, someone may be faulting
* the buffer into the buffer pool.
*/
PinBuffer(buf);
inProgress = (buf->flags & BM_IO_IN_PROGRESS);
*foundPtr = TRUE;
if (inProgress) /* confirm end of IO */
{
WaitIO(buf, BufMgrLock);
inProgress = (buf->flags & BM_IO_IN_PROGRESS);
}
if (BUFFER_IS_BROKEN(buf))
{
/* I couldn't understand the following old comment.
* If there's no IO for the buffer and the buffer
* is BROKEN,it should be read again. So start a
* new buffer IO here.
*
* wierd race condition:
*
* We were waiting for someone else to read the buffer. While
* we were waiting, the reader boof'd in some way, so the
* contents of the buffer are still invalid. By saying
* that we didn't find it, we can make the caller
* reinitialize the buffer. If two processes are waiting
* for this block, both will read the block. The second
* one to finish may overwrite any updates made by the
* first. (Assume higher level synchronization prevents
* this from happening).
*
* This is never going to happen, don't worry about it.
*/
*foundPtr = FALSE;
}
#ifdef BMTRACE
_bm_trace((reln->rd_rel->relisshared ? 0 : MyDatabaseId), RelationGetRelid(reln), blockNum, BufferDescriptorGetBuffer(buf), BMT_ALLOCFND);
#endif /* BMTRACE */
if (!(*foundPtr))
StartBufferIO(buf, true);
SpinRelease(BufMgrLock);
return buf;
}
*foundPtr = FALSE;
/*
* Didn't find it in the buffer pool. We'll have to initialize a new
* buffer. First, grab one from the free list. If it's dirty, flush
* it to disk. Remember to unlock BufMgr spinlock while doing the IOs.
*/
inProgress = FALSE;
for (buf = (BufferDesc *) NULL; buf == (BufferDesc *) NULL;)
{
/* GetFreeBuffer will abort if it can't find a free buffer */
buf = GetFreeBuffer();
/*
* But it can return buf == NULL if we are in aborting transaction
* now and so elog(ERROR,...) in GetFreeBuffer will not abort
* again.
*/
if (buf == NULL)
return NULL;
/*
* There should be exactly one pin on the buffer after it is
* allocated -- ours. If it had a pin it wouldn't have been on
* the free list. No one else could have pinned it between
* GetFreeBuffer and here because we have the BufMgrLock.
*/
Assert(buf->refcount == 0);
buf->refcount = 1;
PrivateRefCount[BufferDescriptorGetBuffer(buf) - 1] = 1;
if (buf->flags & BM_DIRTY)
{
bool smok;
/*
* Set BM_IO_IN_PROGRESS to keep anyone from doing anything
* with the contents of the buffer while we write it out. We
* don't really care if they try to read it, but if they can
* complete a BufferAlloc on it they can then scribble into
* it, and we'd really like to avoid that while we are
* flushing the buffer. Setting this flag should block them
* in WaitIO until we're done.
*/
inProgress = TRUE;
#ifdef HAS_TEST_AND_SET
/*
* All code paths that acquire this lock pin the buffer first;
* since no one had it pinned (it just came off the free
* list), no one else can have this lock.
*/
#endif /* HAS_TEST_AND_SET */
StartBufferIO(buf, false);
/*
* Write the buffer out, being careful to release BufMgrLock
* before starting the I/O.
*
* This #ifndef is here because a few extra semops REALLY kill
* you on machines that don't have spinlocks. If you don't
* operate with much concurrency, well...
*/
smok = BufferReplace(buf, true);
#ifndef OPTIMIZE_SINGLE
SpinAcquire(BufMgrLock);
#endif /* OPTIMIZE_SINGLE */
if (smok == FALSE)
{
elog(NOTICE, "BufferAlloc: cannot write block %u for %s/%s",
buf->tag.blockNum, buf->sb_dbname, buf->sb_relname);
inProgress = FALSE;
buf->flags |= BM_IO_ERROR;
buf->flags &= ~BM_IO_IN_PROGRESS;
TerminateBufferIO(buf);
PrivateRefCount[BufferDescriptorGetBuffer(buf) - 1] = 0;
Assert(buf->refcount > 0);
buf->refcount--;
if (buf->refcount == 0)
{
AddBufferToFreelist(buf);
buf->flags |= BM_FREE;
}
buf = (BufferDesc *) NULL;
}
else
{
/*
* BM_JUST_DIRTIED cleared by BufferReplace and shouldn't
* be setted by anyone. - vadim 01/17/97
*/
if (buf->flags & BM_JUST_DIRTIED)
{
elog(FATAL, "BufferAlloc: content of block %u (%s) changed while flushing",
buf->tag.blockNum, buf->sb_relname);
}
else
buf->flags &= ~BM_DIRTY;
}
/*
* Somebody could have pinned the buffer while we were doing
* the I/O and had given up the BufMgrLock (though they would
* be waiting for us to clear the BM_IO_IN_PROGRESS flag).
* That's why this is a loop -- if so, we need to clear the
* I/O flags, remove our pin and start all over again.
*
* People may be making buffers free at any time, so there's no
* reason to think that we have an immediate disaster on our
* hands.
*/
if (buf && buf->refcount > 1)
{
inProgress = FALSE;
buf->flags &= ~BM_IO_IN_PROGRESS;
TerminateBufferIO(buf);
PrivateRefCount[BufferDescriptorGetBuffer(buf) - 1] = 0;
buf->refcount--;
buf = (BufferDesc *) NULL;
}
/*
* Somebody could have allocated another buffer for the same
* block we are about to read in. (While we flush out the
* dirty buffer, we don't hold the lock and someone could have
* allocated another buffer for the same block. The problem is
* we haven't gotten around to insert the new tag into the
* buffer table. So we need to check here. -ay 3/95
*/
buf2 = BufTableLookup(&newTag);
if (buf2 != NULL)
{
/*
* Found it. Someone has already done what we're about to
* do. We'll just handle this as if it were found in the
* buffer pool in the first place.
*/
if (buf != NULL)
{
TerminateBufferIO(buf);
/* give up the buffer since we don't need it any more */
PrivateRefCount[BufferDescriptorGetBuffer(buf) - 1] = 0;
Assert(buf->refcount > 0);
buf->refcount--;
if (buf->refcount == 0)
{
AddBufferToFreelist(buf);
buf->flags |= BM_FREE;
}
buf->flags &= ~BM_IO_IN_PROGRESS;
}
PinBuffer(buf2);
inProgress = (buf2->flags & BM_IO_IN_PROGRESS);
*foundPtr = TRUE;
if (inProgress)
{
WaitIO(buf2, BufMgrLock);
inProgress = (buf2->flags & BM_IO_IN_PROGRESS);
}
if (BUFFER_IS_BROKEN(buf2))
*foundPtr = FALSE;
if (!(*foundPtr))
StartBufferIO(buf2, true);
SpinRelease(BufMgrLock);
return buf2;
}
}
}
/*
* At this point we should have the sole pin on a non-dirty buffer and
* we may or may not already have the BM_IO_IN_PROGRESS flag set.
*/
/*
* Change the name of the buffer in the lookup table:
*
* Need to update the lookup table before the read starts. If someone
* comes along looking for the buffer while we are reading it in, we
* don't want them to allocate a new buffer. For the same reason, we
* didn't want to erase the buf table entry for the buffer we were
* writing back until now, either.
*/
if (!BufTableDelete(buf))
{
SpinRelease(BufMgrLock);
elog(FATAL, "buffer wasn't in the buffer table\n");
}
/* record the database name and relation name for this buffer */
strcpy(buf->sb_relname, RelationGetPhysicalRelationName(reln));
strcpy(buf->sb_dbname, DatabaseName);
INIT_BUFFERTAG(&(buf->tag), reln, blockNum);
if (!BufTableInsert(buf))
{
SpinRelease(BufMgrLock);
elog(FATAL, "Buffer in lookup table twice \n");
}
/*
* Buffer contents are currently invalid. Have to mark IO IN PROGRESS
* so no one fiddles with them until the read completes. If this
* routine has been called simply to allocate a buffer, no io will be
* attempted, so the flag isnt set.
*/
if (!inProgress)
{
StartBufferIO(buf, true);
}
else
ContinueBufferIO(buf, true);
#ifdef BMTRACE
_bm_trace((reln->rd_rel->relisshared ? 0 : MyDatabaseId), RelationGetRelid(reln), blockNum, BufferDescriptorGetBuffer(buf), BMT_ALLOCNOTFND);
#endif /* BMTRACE */
SpinRelease(BufMgrLock);
return buf;
}
/*
* WriteBuffer
*
* Pushes buffer contents to disk if WriteMode is BUFFER_FLUSH_WRITE.
* Otherwise, marks contents as dirty.
*
* Assume that buffer is pinned. Assume that reln is
* valid.
*
* Side Effects:
* Pin count is decremented.
*/
#undef WriteBuffer
int
WriteBuffer(Buffer buffer)
{
BufferDesc *bufHdr;
if (WriteMode == BUFFER_FLUSH_WRITE)
return FlushBuffer(buffer, TRUE);
else
{
if (BufferIsLocal(buffer))
return WriteLocalBuffer(buffer, TRUE);
if (BAD_BUFFER_ID(buffer))
return FALSE;
bufHdr = &BufferDescriptors[buffer - 1];
SharedBufferChanged = true;
SpinAcquire(BufMgrLock);
Assert(bufHdr->refcount > 0);
bufHdr->flags |= (BM_DIRTY | BM_JUST_DIRTIED);
UnpinBuffer(bufHdr);
SpinRelease(BufMgrLock);
CommitInfoNeedsSave[buffer - 1] = 0;
}
return TRUE;
}
#ifdef NOT_USED
void
WriteBuffer_Debug(char *file, int line, Buffer buffer)
{
WriteBuffer(buffer);
if (ShowPinTrace && BufferIsLocal(buffer) && is_userbuffer(buffer))
{
BufferDesc *buf;
buf = &BufferDescriptors[buffer - 1];
fprintf(stderr, "UNPIN(WR) %ld relname = %s, blockNum = %d, \
refcount = %ld, file: %s, line: %d\n",
buffer, buf->sb_relname, buf->tag.blockNum,
PrivateRefCount[buffer - 1], file, line);
}
}
#endif
/*
* DirtyBufferCopy() -- For a given dbid/relid/blockno, if the buffer is
* in the cache and is dirty, mark it clean and copy
* it to the requested location. This is a logical
* write, and has been installed to support the cache
* management code for write-once storage managers.
*
* DirtyBufferCopy() -- Copy a given dirty buffer to the requested
* destination.
*
* We treat this as a write. If the requested buffer is in the pool
* and is dirty, we copy it to the location requested and mark it
* clean. This routine supports the Sony jukebox storage manager,
* which agrees to take responsibility for the data once we mark
* it clean.
*
* NOTE: used by sony jukebox code in postgres 4.2 - ay 2/95
*/
#ifdef NOT_USED
void
DirtyBufferCopy(Oid dbid, Oid relid, BlockNumber blkno, char *dest)
{
BufferDesc *buf;
BufferTag btag;
btag.relId.relId = relid;
btag.relId.dbId = dbid;
btag.blockNum = blkno;
SpinAcquire(BufMgrLock);
buf = BufTableLookup(&btag);
if (buf == (BufferDesc *) NULL
|| !(buf->flags & BM_DIRTY)
|| !(buf->flags & BM_VALID))
{
SpinRelease(BufMgrLock);
return;
}
/*
* hate to do this holding the lock, but release and reacquire is
* slower
*/
memmove(dest, (char *) MAKE_PTR(buf->data), BLCKSZ);
buf->flags &= ~BM_DIRTY;
SpinRelease(BufMgrLock);
}
#endif
/*
* FlushBuffer -- like WriteBuffer, but force the page to disk.
*
* 'buffer' is known to be dirty/pinned, so there should not be a
* problem reading the BufferDesc members without the BufMgrLock
* (nobody should be able to change tags, flags, etc. out from under
* us).
*/
static int
FlushBuffer(Buffer buffer, bool release)
{
BufferDesc *bufHdr;
Oid bufdb;
Relation bufrel;
int status;
if (BufferIsLocal(buffer))
return FlushLocalBuffer(buffer, release) ? STATUS_OK : STATUS_ERROR;
if (BAD_BUFFER_ID(buffer))
return STATUS_ERROR;
bufHdr = &BufferDescriptors[buffer - 1];
bufdb = bufHdr->tag.relId.dbId;
Assert(bufdb == MyDatabaseId || bufdb == (Oid) NULL);
bufrel = RelationIdCacheGetRelation(bufHdr->tag.relId.relId);
Assert(bufrel != (Relation) NULL);
SharedBufferChanged = true;
/* To check if block content changed while flushing. - vadim 01/17/97 */
SpinAcquire(BufMgrLock);
WaitIO(bufHdr, BufMgrLock); /* confirm end of IO */
bufHdr->flags &= ~BM_JUST_DIRTIED;
StartBufferIO(bufHdr, false); /* output IO start */
SpinRelease(BufMgrLock);
status = smgrflush(DEFAULT_SMGR, bufrel, bufHdr->tag.blockNum,
(char *) MAKE_PTR(bufHdr->data));
/* drop relcache refcnt incremented by RelationIdCacheGetRelation */
RelationDecrementReferenceCount(bufrel);
if (status == SM_FAIL)
{
elog(ERROR, "FlushBuffer: cannot flush block %u of the relation %s",
bufHdr->tag.blockNum, bufHdr->sb_relname);
return STATUS_ERROR;
}
BufferFlushCount++;
SpinAcquire(BufMgrLock);
bufHdr->flags &= ~BM_IO_IN_PROGRESS; /* mark IO finished */
TerminateBufferIO(bufHdr); /* output IO finished */
/*
* If this buffer was marked by someone as DIRTY while we were
* flushing it out we must not clear DIRTY flag - vadim 01/17/97
*/
if (bufHdr->flags & BM_JUST_DIRTIED)
{
elog(NOTICE, "FlushBuffer: content of block %u (%s) changed while flushing",
bufHdr->tag.blockNum, bufHdr->sb_relname);
}
else
bufHdr->flags &= ~BM_DIRTY;
if (release)
UnpinBuffer(bufHdr);
SpinRelease(BufMgrLock);
CommitInfoNeedsSave[buffer - 1] = 0;
return STATUS_OK;
}
/*
* WriteNoReleaseBuffer -- like WriteBuffer, but do not unpin the buffer
* when the operation is complete.
*
* We know that the buffer is for a relation in our private cache,
* because this routine is called only to write out buffers that
* were changed by the executing backend.
*/
int
WriteNoReleaseBuffer(Buffer buffer)
{
BufferDesc *bufHdr;
if (WriteMode == BUFFER_FLUSH_WRITE)
return FlushBuffer(buffer, FALSE);
else
{
if (BufferIsLocal(buffer))
return WriteLocalBuffer(buffer, FALSE);
if (BAD_BUFFER_ID(buffer))
return STATUS_ERROR;
bufHdr = &BufferDescriptors[buffer - 1];
SharedBufferChanged = true;
SpinAcquire(BufMgrLock);
bufHdr->flags |= (BM_DIRTY | BM_JUST_DIRTIED);
SpinRelease(BufMgrLock);
CommitInfoNeedsSave[buffer - 1] = 0;
}
return STATUS_OK;
}
#undef ReleaseAndReadBuffer
/*
* ReleaseAndReadBuffer -- combine ReleaseBuffer() and ReadBuffer()
* so that only one semop needs to be called.
*
*/
Buffer
ReleaseAndReadBuffer(Buffer buffer,
Relation relation,
BlockNumber blockNum)
{
BufferDesc *bufHdr;
Buffer retbuf;
if (BufferIsLocal(buffer))
{
Assert(LocalRefCount[-buffer - 1] > 0);
LocalRefCount[-buffer - 1]--;
}
else
{
if (BufferIsValid(buffer))
{
bufHdr = &BufferDescriptors[buffer - 1];
Assert(PrivateRefCount[buffer - 1] > 0);
PrivateRefCount[buffer - 1]--;
if (PrivateRefCount[buffer - 1] == 0)
{
SpinAcquire(BufMgrLock);
Assert(bufHdr->refcount > 0);
bufHdr->refcount--;
if (bufHdr->refcount == 0)
{
AddBufferToFreelist(bufHdr);
bufHdr->flags |= BM_FREE;
}
if (CommitInfoNeedsSave[buffer - 1])
{
bufHdr->flags |= (BM_DIRTY | BM_JUST_DIRTIED);
CommitInfoNeedsSave[buffer - 1] = 0;
}
retbuf = ReadBufferWithBufferLock(relation, blockNum, true);
return retbuf;
}
}
}
return ReadBuffer(relation, blockNum);
}
/*
* BufferSync -- Flush all dirty buffers in the pool.
*
* This is called at transaction commit time. It does the wrong thing,
* right now. We should flush only our own changes to stable storage,
* and we should obey the lock protocol on the buffer manager metadata
* as we do it. Also, we need to be sure that no other transaction is
* modifying the page as we flush it. This is only a problem for objects
* that use a non-two-phase locking protocol, like btree indices. For
* those objects, we would like to set a write lock for the duration of
* our IO. Another possibility is to code updates to btree pages
* carefully, so that writing them out out of order cannot cause
* any unrecoverable errors.
*
* I don't want to think hard about this right now, so I will try
* to come back to it later.
*/
static void
BufferSync()
{
int i;
Oid bufdb;
Oid bufrel;
Relation reln;
BufferDesc *bufHdr;
int status;
SpinAcquire(BufMgrLock);
for (i = 0, bufHdr = BufferDescriptors; i < NBuffers; i++, bufHdr++)
{
if ((bufHdr->flags & BM_VALID) && (bufHdr->flags & BM_DIRTY))
{
bufdb = bufHdr->tag.relId.dbId;
bufrel = bufHdr->tag.relId.relId;
if (bufdb == MyDatabaseId || bufdb == (Oid) 0)
{
reln = RelationIdCacheGetRelation(bufrel);
/*
* We have to pin buffer to keep anyone from stealing it
* from the buffer pool while we are flushing it or
* waiting in WaitIO. It's bad for GetFreeBuffer in
* BufferAlloc, but there is no other way to prevent
* writing into disk block data from some other buffer,
* getting smgr status of some other block and clearing
* BM_DIRTY of ... - VAdim 09/16/96
*/
PinBuffer(bufHdr);
if (bufHdr->flags & BM_IO_IN_PROGRESS)
{
WaitIO(bufHdr, BufMgrLock);
UnpinBuffer(bufHdr);
if (bufHdr->flags & BM_IO_ERROR)
{
elog(ERROR, "BufferSync: write error %u for %s",
bufHdr->tag.blockNum, bufHdr->sb_relname);
}
/* drop refcnt from RelationIdCacheGetRelation */
if (reln != (Relation) NULL)
RelationDecrementReferenceCount(reln);
continue;
}
/*
* To check if block content changed while flushing (see
* below). - vadim 01/17/97
*/
WaitIO(bufHdr, BufMgrLock); /* confirm end of IO */
bufHdr->flags &= ~BM_JUST_DIRTIED;
StartBufferIO(bufHdr, false); /* output IO start */
/*
* If we didn't have the reldesc in our local cache, flush
* this page out using the 'blind write' storage manager
* routine. If we did find it, use the standard
* interface.
*/
#ifndef OPTIMIZE_SINGLE
SpinRelease(BufMgrLock);
#endif /* OPTIMIZE_SINGLE */
if (reln == (Relation) NULL)
{
status = smgrblindwrt(DEFAULT_SMGR, bufHdr->sb_dbname,
bufHdr->sb_relname, bufdb, bufrel,
bufHdr->tag.blockNum,
(char *) MAKE_PTR(bufHdr->data));
}
else
{
status = smgrwrite(DEFAULT_SMGR, reln,
bufHdr->tag.blockNum,
(char *) MAKE_PTR(bufHdr->data));
}
#ifndef OPTIMIZE_SINGLE
SpinAcquire(BufMgrLock);
#endif /* OPTIMIZE_SINGLE */
UnpinBuffer(bufHdr);
if (status == SM_FAIL)
{
bufHdr->flags |= BM_IO_ERROR;
elog(ERROR, "BufferSync: cannot write %u for %s",
bufHdr->tag.blockNum, bufHdr->sb_relname);
}
bufHdr->flags &= ~BM_IO_IN_PROGRESS; /* mark IO finished */
TerminateBufferIO(bufHdr); /* Sync IO finished */
BufferFlushCount++;
/*
* If this buffer was marked by someone as DIRTY while we
* were flushing it out we must not clear DIRTY flag -
* vadim 01/17/97
*/
if (!(bufHdr->flags & BM_JUST_DIRTIED))
bufHdr->flags &= ~BM_DIRTY;
/* drop refcnt from RelationIdCacheGetRelation */
if (reln != (Relation) NULL)
RelationDecrementReferenceCount(reln);
}
}
}
SpinRelease(BufMgrLock);
LocalBufferSync();
}
/*
* WaitIO -- Block until the IO_IN_PROGRESS flag on 'buf' is cleared.
*
* Should be entered with buffer manager spinlock held; releases it before
* waiting and re-acquires it afterwards.
*
* OLD NOTES:
* Because IO_IN_PROGRESS conflicts are
* expected to be rare, there is only one BufferIO
* lock in the entire system. All processes block
* on this semaphore when they try to use a buffer
* that someone else is faulting in. Whenever a
* process finishes an IO and someone is waiting for
* the buffer, BufferIO is signaled (SignalIO). All
* waiting processes then wake up and check to see
* if their buffer is now ready. This implementation
* is simple, but efficient enough if WaitIO is
* rarely called by multiple processes simultaneously.
*
* NEW NOTES:
* The above is true only on machines without test-and-set
* semaphores (which we hope are few, these days). On better
* hardware, each buffer has a spinlock that we can wait on.
*/
#ifdef HAS_TEST_AND_SET
static void
WaitIO(BufferDesc *buf, SPINLOCK spinlock)
{
/*
* Changed to wait until there's no IO - Inoue 01/13/2000
*/
while ((buf->flags & BM_IO_IN_PROGRESS) != 0)
{
SpinRelease(spinlock);
S_LOCK(&(buf->io_in_progress_lock));
S_UNLOCK(&(buf->io_in_progress_lock));
SpinAcquire(spinlock);
}
}
#else /* !HAS_TEST_AND_SET */
IpcSemaphoreId WaitIOSemId;
IpcSemaphoreId WaitCLSemId;
static void
WaitIO(BufferDesc *buf, SPINLOCK spinlock)
{
bool inProgress;
for (;;)
{
/* wait until someone releases IO lock */
(*NWaitIOBackendP)++;
SpinRelease(spinlock);
IpcSemaphoreLock(WaitIOSemId, 0, 1);
SpinAcquire(spinlock);
inProgress = (buf->flags & BM_IO_IN_PROGRESS);
if (!inProgress)
break;
}
}
/*
* SignalIO
*/
static void
SignalIO(BufferDesc *buf)
{
/* somebody better be waiting. */
Assert(buf->refcount > 1);
IpcSemaphoreUnlock(WaitIOSemId, 0, *NWaitIOBackendP);
*NWaitIOBackendP = 0;
}
#endif /* HAS_TEST_AND_SET */
long NDirectFileRead; /* some I/O's are direct file access.
* bypass bufmgr */
long NDirectFileWrite; /* e.g., I/O in psort and hashjoin. */
void
PrintBufferUsage(FILE *statfp)
{
float hitrate;
float localhitrate;
if (ReadBufferCount == 0)
hitrate = 0.0;
else
hitrate = (float) BufferHitCount *100.0 / ReadBufferCount;
if (ReadLocalBufferCount == 0)
localhitrate = 0.0;
else
localhitrate = (float) LocalBufferHitCount *100.0 / ReadLocalBufferCount;
fprintf(statfp, "!\tShared blocks: %10ld read, %10ld written, buffer hit rate = %.2f%%\n",
ReadBufferCount - BufferHitCount, BufferFlushCount, hitrate);
fprintf(statfp, "!\tLocal blocks: %10ld read, %10ld written, buffer hit rate = %.2f%%\n",
ReadLocalBufferCount - LocalBufferHitCount, LocalBufferFlushCount, localhitrate);
fprintf(statfp, "!\tDirect blocks: %10ld read, %10ld written\n",
NDirectFileRead, NDirectFileWrite);
}
void
ResetBufferUsage()
{
BufferHitCount = 0;
ReadBufferCount = 0;
BufferFlushCount = 0;
LocalBufferHitCount = 0;
ReadLocalBufferCount = 0;
LocalBufferFlushCount = 0;
NDirectFileRead = 0;
NDirectFileWrite = 0;
}
/* ----------------------------------------------
* ResetBufferPool
*
* this routine is supposed to be called when a transaction aborts.
* it will release all the buffer pins held by the transaction.
*
* ----------------------------------------------
*/
void
ResetBufferPool()
{
int i;
for (i = 0; i < NBuffers; i++)
{
if (PrivateRefCount[i] != 0)
{
BufferDesc *buf = &BufferDescriptors[i];
SpinAcquire(BufMgrLock);
Assert(buf->refcount > 0);
buf->refcount--;
if (buf->refcount == 0)
{
AddBufferToFreelist(buf);
buf->flags |= BM_FREE;
}
SpinRelease(BufMgrLock);
}
PrivateRefCount[i] = 0;
CommitInfoNeedsSave[i] = 0;
}
ResetLocalBufferPool();
}
/* -----------------------------------------------
* BufferPoolCheckLeak
*
* check if there is buffer leak
*
* -----------------------------------------------
*/
int
BufferPoolCheckLeak()
{
int i;
int result = 0;
for (i = 1; i <= NBuffers; i++)
{
if (PrivateRefCount[i - 1] != 0)
{
BufferDesc *buf = &(BufferDescriptors[i - 1]);
elog(NOTICE,
"Buffer Leak: [%03d] (freeNext=%ld, freePrev=%ld, \
relname=%s, blockNum=%d, flags=0x%x, refcount=%d %ld)",
i - 1, buf->freeNext, buf->freePrev,
buf->sb_relname, buf->tag.blockNum, buf->flags,
buf->refcount, PrivateRefCount[i - 1]);
result = 1;
}
}
return result;
}
/* ------------------------------------------------
* FlushBufferPool
*
* flush all dirty blocks in buffer pool to disk
*
* ------------------------------------------------
*/
void
FlushBufferPool(void)
{
BufferSync();
smgrcommit();
}
/*
* BufferGetBlockNumber
* Returns the block number associated with a buffer.
*
* Note:
* Assumes that the buffer is valid.
*/
BlockNumber
BufferGetBlockNumber(Buffer buffer)
{
Assert(BufferIsValid(buffer));
/* XXX should be a critical section */
if (BufferIsLocal(buffer))
return LocalBufferDescriptors[-buffer - 1].tag.blockNum;
else
return BufferDescriptors[buffer - 1].tag.blockNum;
}
#ifdef NOT_USED
/*
* BufferGetRelation
* Returns the relation desciptor associated with a buffer.
*
* Note:
* Assumes buffer is valid.
*/
Relation
BufferGetRelation(Buffer buffer)
{
Relation relation;
Oid relid;
Assert(BufferIsValid(buffer));
Assert(!BufferIsLocal(buffer)); /* not supported for local buffers */
/* XXX should be a critical section */
relid = BufferDescriptors[buffer - 1].tag.relId.relId;
relation = RelationIdGetRelation(relid);
Assert(relation);
/* drop relcache refcnt incremented by RelationIdGetRelation */
RelationDecrementReferenceCount(relation);
if (RelationHasReferenceCountZero(relation))
{
/*
* XXX why??
*/
RelationIncrementReferenceCount(relation);
}
return relation;
}
#endif
/*
* BufferReplace
*
* Flush the buffer corresponding to 'bufHdr'
*
*/
static int
BufferReplace(BufferDesc *bufHdr, bool bufferLockHeld)
{
Relation reln;
Oid bufdb,
bufrel;
int status;
if (!bufferLockHeld)
SpinAcquire(BufMgrLock);
/*
* first try to find the reldesc in the cache, if no luck, don't
* bother to build the reldesc from scratch, just do a blind write.
*/
bufdb = bufHdr->tag.relId.dbId;
bufrel = bufHdr->tag.relId.relId;
if (bufdb == MyDatabaseId || bufdb == (Oid) NULL)
reln = RelationIdCacheGetRelation(bufrel);
else
reln = (Relation) NULL;
/* To check if block content changed while flushing. - vadim 01/17/97 */
bufHdr->flags &= ~BM_JUST_DIRTIED;
SpinRelease(BufMgrLock);
if (reln != (Relation) NULL)
{
status = smgrflush(DEFAULT_SMGR, reln, bufHdr->tag.blockNum,
(char *) MAKE_PTR(bufHdr->data));
}
else
{
/* blind write always flushes */
status = smgrblindwrt(DEFAULT_SMGR, bufHdr->sb_dbname,
bufHdr->sb_relname, bufdb, bufrel,
bufHdr->tag.blockNum,
(char *) MAKE_PTR(bufHdr->data));
}
/* drop relcache refcnt incremented by RelationIdCacheGetRelation */
if (reln != (Relation) NULL)
RelationDecrementReferenceCount(reln);
if (status == SM_FAIL)
return FALSE;
BufferFlushCount++;
return TRUE;
}
/*
* RelationGetNumberOfBlocks
* Returns the buffer descriptor associated with a page in a relation.
*
* Note:
* XXX may fail for huge relations.
* XXX should be elsewhere.
* XXX maybe should be hidden
*/
BlockNumber
RelationGetNumberOfBlocks(Relation relation)
{
return ((relation->rd_myxactonly) ? relation->rd_nblocks :
smgrnblocks(DEFAULT_SMGR, relation));
}
/* ---------------------------------------------------------------------
* ReleaseRelationBuffers
*
* this function unmarks all the dirty pages of a relation
* in the buffer pool so that at the end of transaction
* these pages will not be flushed. This is used when the
* relation is about to be deleted. We assume that the caller
* holds an exclusive lock on the relation, which should assure
* that no new buffers will be acquired for the rel meanwhile.
*
* XXX currently it sequentially searches the buffer pool, should be
* changed to more clever ways of searching.
* --------------------------------------------------------------------
*/
void
ReleaseRelationBuffers(Relation rel)
{
Oid relid = RelationGetRelid(rel);
bool holding = false;
int i;
BufferDesc *buf;
if (rel->rd_myxactonly)
{
for (i = 0; i < NLocBuffer; i++)
{
buf = &LocalBufferDescriptors[i];
if (buf->tag.relId.relId == relid)
buf->flags &= ~ ( BM_DIRTY | BM_JUST_DIRTIED);
}
return;
}
for (i = 1; i <= NBuffers; i++)
{
buf = &BufferDescriptors[i - 1];
if (!holding)
{
SpinAcquire(BufMgrLock);
holding = true;
}
recheck:
if (buf->tag.relId.dbId == MyDatabaseId &&
buf->tag.relId.relId == relid)
{
/*
* If there is I/O in progress, better wait till it's done;
* don't want to delete the relation out from under someone
* who's just trying to flush the buffer!
*/
if (buf->flags & BM_IO_IN_PROGRESS)
{
WaitIO(buf, BufMgrLock);
/* By now, the buffer very possibly belongs to some other
* rel, so check again before proceeding.
*/
goto recheck;
}
/* Now we can do what we came for */
buf->flags &= ~ ( BM_DIRTY | BM_JUST_DIRTIED);
CommitInfoNeedsSave[i - 1] = 0;
/*
* Release any refcount we may have.
*
* This is very probably dead code, and if it isn't then it's
* probably wrong. I added the Assert to find out --- tgl 11/99.
*/
if (!(buf->flags & BM_FREE))
{
/* Assert checks that buffer will actually get freed! */
Assert(PrivateRefCount[i - 1] == 1 &&
buf->refcount == 1);
/* ReleaseBuffer expects we do not hold the lock at entry */
SpinRelease(BufMgrLock);
holding = false;
ReleaseBuffer(i);
}
}
}
if (holding)
SpinRelease(BufMgrLock);
}
/* ---------------------------------------------------------------------
* DropBuffers
*
* This function marks all the buffers in the buffer cache for a
* particular database as clean. This is used when we destroy a
* database, to avoid trying to flush data to disk when the directory
* tree no longer exists. Implementation is pretty similar to
* ReleaseRelationBuffers() which is for destroying just one relation.
* --------------------------------------------------------------------
*/
void
DropBuffers(Oid dbid)
{
int i;
BufferDesc *buf;
SpinAcquire(BufMgrLock);
for (i = 1; i <= NBuffers; i++)
{
buf = &BufferDescriptors[i - 1];
recheck:
if (buf->tag.relId.dbId == dbid)
{
/*
* If there is I/O in progress, better wait till it's done;
* don't want to delete the database out from under someone
* who's just trying to flush the buffer!
*/
if (buf->flags & BM_IO_IN_PROGRESS)
{
WaitIO(buf, BufMgrLock);
/* By now, the buffer very possibly belongs to some other
* DB, so check again before proceeding.
*/
goto recheck;
}
/* Now we can do what we came for */
buf->flags &= ~ ( BM_DIRTY | BM_JUST_DIRTIED);
/*
* The thing should be free, if caller has checked that
* no backends are running in that database.
*/
Assert(buf->flags & BM_FREE);
}
}
SpinRelease(BufMgrLock);
}
/* -----------------------------------------------------------------
* PrintBufferDescs
*
* this function prints all the buffer descriptors, for debugging
* use only.
* -----------------------------------------------------------------
*/
void
PrintBufferDescs()
{
int i;
BufferDesc *buf = BufferDescriptors;
if (IsUnderPostmaster)
{
SpinAcquire(BufMgrLock);
for (i = 0; i < NBuffers; ++i, ++buf)
{
elog(DEBUG, "[%02d] (freeNext=%ld, freePrev=%ld, relname=%s, \
blockNum=%d, flags=0x%x, refcount=%d %ld)",
i, buf->freeNext, buf->freePrev,
buf->sb_relname, buf->tag.blockNum, buf->flags,
buf->refcount, PrivateRefCount[i]);
}
SpinRelease(BufMgrLock);
}
else
{
/* interactive backend */
for (i = 0; i < NBuffers; ++i, ++buf)
{
printf("[%-2d] (%s, %d) flags=0x%x, refcnt=%d %ld)\n",
i, buf->sb_relname, buf->tag.blockNum,
buf->flags, buf->refcount, PrivateRefCount[i]);
}
}
}
void
PrintPinnedBufs()
{
int i;
BufferDesc *buf = BufferDescriptors;
SpinAcquire(BufMgrLock);
for (i = 0; i < NBuffers; ++i, ++buf)
{
if (PrivateRefCount[i] > 0)
elog(NOTICE, "[%02d] (freeNext=%ld, freePrev=%ld, relname=%s, \
blockNum=%d, flags=0x%x, refcount=%d %ld)\n",
i, buf->freeNext, buf->freePrev, buf->sb_relname,
buf->tag.blockNum, buf->flags,
buf->refcount, PrivateRefCount[i]);
}
SpinRelease(BufMgrLock);
}
/*
* BufferPoolBlowaway
*
* this routine is solely for the purpose of experiments -- sometimes
* you may want to blowaway whatever is left from the past in buffer
* pool and start measuring some performance with a clean empty buffer
* pool.
*/
#ifdef NOT_USED
void
BufferPoolBlowaway()
{
int i;
BufferSync();
for (i = 1; i <= NBuffers; i++)
{
if (BufferIsValid(i))
{
while (BufferIsValid(i))
ReleaseBuffer(i);
}
BufTableDelete(&BufferDescriptors[i - 1]);
}
}
#endif
/* ---------------------------------------------------------------------
* FlushRelationBuffers
*
* This function removes from the buffer pool all pages of a relation
* that have blocknumber >= specified block. If doFlush is true,
* dirty buffers are written out --- otherwise it's an error for any
* of the buffers to be dirty.
*
* This is used by VACUUM before truncating the relation to the given
* number of blocks. For VACUUM, we pass doFlush = false since it would
* mean a bug in VACUUM if any of the unwanted pages were still dirty.
* (TRUNCATE TABLE also uses it in the same way.)
*
* This is also used by RENAME TABLE (with block = 0 and doFlush = true)
* to clear out the buffer cache before renaming the physical files of
* a relation. Without that, some other backend might try to do a
* blind write of a buffer page (relying on the sb_relname of the buffer)
* and fail because it's not got the right filename anymore.
*
* In both cases, the caller should be holding AccessExclusiveLock on
* the target relation to ensure that no other backend is busy reading
* more blocks of the relation...
*
* Returns: 0 - Ok, -1 - DIRTY, -2 - PINNED
*
* XXX currently it sequentially searches the buffer pool, should be
* changed to more clever ways of searching.
* --------------------------------------------------------------------
*/
int
FlushRelationBuffers(Relation rel, BlockNumber block, bool doFlush)
{
int i;
BufferDesc *buf;
if (rel->rd_myxactonly)
{
for (i = 0; i < NLocBuffer; i++)
{
buf = &LocalBufferDescriptors[i];
if (buf->tag.relId.relId == RelationGetRelid(rel) &&
buf->tag.blockNum >= block)
{
if (buf->flags & BM_DIRTY)
{
if (doFlush)
{
if (FlushBuffer(-i-1, false) != STATUS_OK)
{
elog(NOTICE, "FlushRelationBuffers(%s (local), %u): block %u is dirty, could not flush it",
RelationGetRelationName(rel),
block, buf->tag.blockNum);
return -1;
}
}
else
{
elog(NOTICE, "FlushRelationBuffers(%s (local), %u): block %u is dirty",
RelationGetRelationName(rel),
block, buf->tag.blockNum);
return -1;
}
}
if (LocalRefCount[i] > 0)
{
elog(NOTICE, "FlushRelationBuffers(%s (local), %u): block %u is referenced (%ld)",
RelationGetRelationName(rel), block,
buf->tag.blockNum, LocalRefCount[i]);
return -2;
}
buf->tag.relId.relId = InvalidOid;
}
}
return 0;
}
SpinAcquire(BufMgrLock);
for (i = 0; i < NBuffers; i++)
{
buf = &BufferDescriptors[i];
if (buf->tag.relId.dbId == MyDatabaseId &&
buf->tag.relId.relId == RelationGetRelid(rel) &&
buf->tag.blockNum >= block)
{
if (buf->flags & BM_DIRTY)
{
if (doFlush)
{
SpinRelease(BufMgrLock);
if (FlushBuffer(i+1, false) != STATUS_OK)
{
elog(NOTICE, "FlushRelationBuffers(%s, %u): block %u is dirty (private %ld, global %d), could not flush it",
buf->sb_relname, block, buf->tag.blockNum,
PrivateRefCount[i], buf->refcount);
return -1;
}
SpinAcquire(BufMgrLock);
}
else
{
SpinRelease(BufMgrLock);
elog(NOTICE, "FlushRelationBuffers(%s, %u): block %u is dirty (private %ld, global %d)",
buf->sb_relname, block, buf->tag.blockNum,
PrivateRefCount[i], buf->refcount);
return -1;
}
}
if (!(buf->flags & BM_FREE))
{
SpinRelease(BufMgrLock);
elog(NOTICE, "FlushRelationBuffers(%s, %u): block %u is referenced (private %ld, global %d)",
buf->sb_relname, block, buf->tag.blockNum,
PrivateRefCount[i], buf->refcount);
return -2;
}
BufTableDelete(buf);
}
}
SpinRelease(BufMgrLock);
return 0;
}
#undef ReleaseBuffer
/*
* ReleaseBuffer -- remove the pin on a buffer without
* marking it dirty.
*
*/
int
ReleaseBuffer(Buffer buffer)
{
BufferDesc *bufHdr;
if (BufferIsLocal(buffer))
{
Assert(LocalRefCount[-buffer - 1] > 0);
LocalRefCount[-buffer - 1]--;
return STATUS_OK;
}
if (BAD_BUFFER_ID(buffer))
return STATUS_ERROR;
bufHdr = &BufferDescriptors[buffer - 1];
Assert(PrivateRefCount[buffer - 1] > 0);
PrivateRefCount[buffer - 1]--;
if (PrivateRefCount[buffer - 1] == 0)
{
SpinAcquire(BufMgrLock);
Assert(bufHdr->refcount > 0);
bufHdr->refcount--;
if (bufHdr->refcount == 0)
{
AddBufferToFreelist(bufHdr);
bufHdr->flags |= BM_FREE;
}
if (CommitInfoNeedsSave[buffer - 1])
{
bufHdr->flags |= (BM_DIRTY | BM_JUST_DIRTIED);
CommitInfoNeedsSave[buffer - 1] = 0;
}
SpinRelease(BufMgrLock);
}
return STATUS_OK;
}
#ifdef NOT_USED
void
IncrBufferRefCount_Debug(char *file, int line, Buffer buffer)
{
IncrBufferRefCount(buffer);
if (ShowPinTrace && !BufferIsLocal(buffer) && is_userbuffer(buffer))
{
BufferDesc *buf = &BufferDescriptors[buffer - 1];
fprintf(stderr, "PIN(Incr) %ld relname = %s, blockNum = %d, \
refcount = %ld, file: %s, line: %d\n",
buffer, buf->sb_relname, buf->tag.blockNum,
PrivateRefCount[buffer - 1], file, line);
}
}
#endif
#ifdef NOT_USED
void
ReleaseBuffer_Debug(char *file, int line, Buffer buffer)
{
ReleaseBuffer(buffer);
if (ShowPinTrace && !BufferIsLocal(buffer) && is_userbuffer(buffer))
{
BufferDesc *buf = &BufferDescriptors[buffer - 1];
fprintf(stderr, "UNPIN(Rel) %ld relname = %s, blockNum = %d, \
refcount = %ld, file: %s, line: %d\n",
buffer, buf->sb_relname, buf->tag.blockNum,
PrivateRefCount[buffer - 1], file, line);
}
}
#endif
#ifdef NOT_USED
int
ReleaseAndReadBuffer_Debug(char *file,
int line,
Buffer buffer,
Relation relation,
BlockNumber blockNum)
{
bool bufferValid;
Buffer b;
bufferValid = BufferIsValid(buffer);
b = ReleaseAndReadBuffer(buffer, relation, blockNum);
if (ShowPinTrace && bufferValid && BufferIsLocal(buffer)
&& is_userbuffer(buffer))
{
BufferDesc *buf = &BufferDescriptors[buffer - 1];
fprintf(stderr, "UNPIN(Rel&Rd) %ld relname = %s, blockNum = %d, \
refcount = %ld, file: %s, line: %d\n",
buffer, buf->sb_relname, buf->tag.blockNum,
PrivateRefCount[buffer - 1], file, line);
}
if (ShowPinTrace && BufferIsLocal(buffer) && is_userbuffer(buffer))
{
BufferDesc *buf = &BufferDescriptors[b - 1];
fprintf(stderr, "PIN(Rel&Rd) %ld relname = %s, blockNum = %d, \
refcount = %ld, file: %s, line: %d\n",
b, buf->sb_relname, buf->tag.blockNum,
PrivateRefCount[b - 1], file, line);
}
return b;
}
#endif
#ifdef BMTRACE
/*
* trace allocations and deallocations in a circular buffer in
* shared memory. check the buffer before doing the allocation,
* and die if there's anything fishy.
*/
_bm_trace(Oid dbId, Oid relId, int blkNo, int bufNo, int allocType)
{
long start,
cur;
bmtrace *tb;
start = *CurTraceBuf;
if (start > 0)
cur = start - 1;
else
cur = BMT_LIMIT - 1;
for (;;)
{
tb = &TraceBuf[cur];
if (tb->bmt_op != BMT_NOTUSED)
{
if (tb->bmt_buf == bufNo)
{
if ((tb->bmt_op == BMT_DEALLOC)
|| (tb->bmt_dbid == dbId && tb->bmt_relid == relId
&& tb->bmt_blkno == blkNo))
goto okay;
/* die holding the buffer lock */
_bm_die(dbId, relId, blkNo, bufNo, allocType, start, cur);
}
}
if (cur == start)
goto okay;
if (cur == 0)
cur = BMT_LIMIT - 1;
else
cur--;
}
okay:
tb = &TraceBuf[start];
tb->bmt_pid = MyProcPid;
tb->bmt_buf = bufNo;
tb->bmt_dbid = dbId;
tb->bmt_relid = relId;
tb->bmt_blkno = blkNo;
tb->bmt_op = allocType;
*CurTraceBuf = (start + 1) % BMT_LIMIT;
}
_bm_die(Oid dbId, Oid relId, int blkNo, int bufNo,
int allocType, long start, long cur)
{
FILE *fp;
bmtrace *tb;
int i;
tb = &TraceBuf[cur];
if ((fp = AllocateFile("/tmp/death_notice", "w")) == NULL)
elog(FATAL, "buffer alloc trace error and can't open log file");
fprintf(fp, "buffer alloc trace detected the following error:\n\n");
fprintf(fp, " buffer %d being %s inconsistently with a previous %s\n\n",
bufNo, (allocType == BMT_DEALLOC ? "deallocated" : "allocated"),
(tb->bmt_op == BMT_DEALLOC ? "deallocation" : "allocation"));
fprintf(fp, "the trace buffer contains:\n");
i = start;
for (;;)
{
tb = &TraceBuf[i];
if (tb->bmt_op != BMT_NOTUSED)
{
fprintf(fp, " [%3d]%spid %d buf %2d for <%d,%u,%d> ",
i, (i == cur ? " ---> " : "\t"),
tb->bmt_pid, tb->bmt_buf,
tb->bmt_dbid, tb->bmt_relid, tb->bmt_blkno);
switch (tb->bmt_op)
{
case BMT_ALLOCFND:
fprintf(fp, "allocate (found)\n");
break;
case BMT_ALLOCNOTFND:
fprintf(fp, "allocate (not found)\n");
break;
case BMT_DEALLOC:
fprintf(fp, "deallocate\n");
break;
default:
fprintf(fp, "unknown op type %d\n", tb->bmt_op);
break;
}
}
i = (i + 1) % BMT_LIMIT;
if (i == start)
break;
}
fprintf(fp, "\noperation causing error:\n");
fprintf(fp, "\tpid %d buf %d for <%d,%u,%d> ",
getpid(), bufNo, dbId, relId, blkNo);
switch (allocType)
{
case BMT_ALLOCFND:
fprintf(fp, "allocate (found)\n");
break;
case BMT_ALLOCNOTFND:
fprintf(fp, "allocate (not found)\n");
break;
case BMT_DEALLOC:
fprintf(fp, "deallocate\n");
break;
default:
fprintf(fp, "unknown op type %d\n", allocType);
break;
}
FreeFile(fp);
kill(getpid(), SIGILL);
}
#endif /* BMTRACE */
int
SetBufferWriteMode(int mode)
{
int old;
old = WriteMode;
WriteMode = mode;
return old;
}
void
SetBufferCommitInfoNeedsSave(Buffer buffer)
{
if (!BufferIsLocal(buffer))
CommitInfoNeedsSave[buffer - 1]++;
}
void
UnlockBuffers()
{
BufferDesc *buf;
int i;
for (i = 0; i < NBuffers; i++)
{
if (BufferLocks[i] == 0)
continue;
Assert(BufferIsValid(i + 1));
buf = &(BufferDescriptors[i]);
#ifdef HAS_TEST_AND_SET
S_LOCK(&(buf->cntx_lock));
#else
IpcSemaphoreLock(WaitCLSemId, 0, IpcExclusiveLock);
#endif
if (BufferLocks[i] & BL_R_LOCK)
{
Assert(buf->r_locks > 0);
(buf->r_locks)--;
}
if (BufferLocks[i] & BL_RI_LOCK)
{
/*
* Someone else could remove our RI lock when acquiring
* W lock. This is possible if we came here from elog(ERROR)
* from IpcSemaphore{Lock|Unlock}(WaitCLSemId). And so we
* don't do Assert(buf->ri_lock) here.
*/
buf->ri_lock = false;
}
if (BufferLocks[i] & BL_W_LOCK)
{
Assert(buf->w_lock);
buf->w_lock = false;
}
#ifdef HAS_TEST_AND_SET
S_UNLOCK(&(buf->cntx_lock));
#else
IpcSemaphoreUnlock(WaitCLSemId, 0, IpcExclusiveLock);
#endif
BufferLocks[i] = 0;
}
}
void
LockBuffer(Buffer buffer, int mode)
{
BufferDesc *buf;
Assert(BufferIsValid(buffer));
if (BufferIsLocal(buffer))
return;
buf = &(BufferDescriptors[buffer - 1]);
#ifdef HAS_TEST_AND_SET
S_LOCK(&(buf->cntx_lock));
#else
IpcSemaphoreLock(WaitCLSemId, 0, IpcExclusiveLock);
#endif
if (mode == BUFFER_LOCK_UNLOCK)
{
if (BufferLocks[buffer - 1] & BL_R_LOCK)
{
Assert(buf->r_locks > 0);
Assert(!(buf->w_lock));
Assert(!(BufferLocks[buffer - 1] & (BL_W_LOCK | BL_RI_LOCK)))
(buf->r_locks)--;
BufferLocks[buffer - 1] &= ~BL_R_LOCK;
}
else if (BufferLocks[buffer - 1] & BL_W_LOCK)
{
Assert(buf->w_lock);
Assert(buf->r_locks == 0);
Assert(!(BufferLocks[buffer - 1] & (BL_R_LOCK | BL_RI_LOCK)))
buf->w_lock = false;
BufferLocks[buffer - 1] &= ~BL_W_LOCK;
}
else
elog(ERROR, "UNLockBuffer: buffer %lu is not locked", buffer);
}
else if (mode == BUFFER_LOCK_SHARE)
{
unsigned i = 0;
Assert(!(BufferLocks[buffer - 1] & (BL_R_LOCK | BL_W_LOCK | BL_RI_LOCK)));
while (buf->ri_lock || buf->w_lock)
{
#ifdef HAS_TEST_AND_SET
S_UNLOCK(&(buf->cntx_lock));
s_lock_sleep(i++);
S_LOCK(&(buf->cntx_lock));
#else
IpcSemaphoreUnlock(WaitCLSemId, 0, IpcExclusiveLock);
s_lock_sleep(i++);
IpcSemaphoreLock(WaitCLSemId, 0, IpcExclusiveLock);
#endif
}
(buf->r_locks)++;
BufferLocks[buffer - 1] |= BL_R_LOCK;
}
else if (mode == BUFFER_LOCK_EXCLUSIVE)
{
unsigned i = 0;
Assert(!(BufferLocks[buffer - 1] & (BL_R_LOCK | BL_W_LOCK | BL_RI_LOCK)));
while (buf->r_locks > 0 || buf->w_lock)
{
if (buf->r_locks > 3 || (BufferLocks[buffer - 1] & BL_RI_LOCK))
{
/*
* Our RI lock might be removed by concurrent W lock
* acquiring (see what we do with RI locks below
* when our own W acquiring succeeded) and so
* we set RI lock again if we already did this.
*/
BufferLocks[buffer - 1] |= BL_RI_LOCK;
buf->ri_lock = true;
}
#ifdef HAS_TEST_AND_SET
S_UNLOCK(&(buf->cntx_lock));
s_lock_sleep(i++);
S_LOCK(&(buf->cntx_lock));
#else
IpcSemaphoreUnlock(WaitCLSemId, 0, IpcExclusiveLock);
s_lock_sleep(i++);
IpcSemaphoreLock(WaitCLSemId, 0, IpcExclusiveLock);
#endif
}
buf->w_lock = true;
BufferLocks[buffer - 1] |= BL_W_LOCK;
if (BufferLocks[buffer - 1] & BL_RI_LOCK)
{
/*
* It's possible to remove RI locks acquired by another
* W lockers here, but they'll take care about it.
*/
buf->ri_lock = false;
BufferLocks[buffer - 1] &= ~BL_RI_LOCK;
}
}
else
elog(ERROR, "LockBuffer: unknown lock mode %d", mode);
#ifdef HAS_TEST_AND_SET
S_UNLOCK(&(buf->cntx_lock));
#else
IpcSemaphoreUnlock(WaitCLSemId, 0, IpcExclusiveLock);
#endif
}
/*
* Functions for IO error handling
*
* Note : We assume that nested buffer IO never occur.
* i.e at most one io_in_progress spinlock is held
* per proc.
*/
static BufferDesc *InProgressBuf = (BufferDesc *)NULL;
static bool IsForInput;
/*
* Function:StartBufferIO
* (Assumptions)
* My process is executing no IO
* BufMgrLock is held
* BM_IO_IN_PROGRESS mask is not set for the buffer
* The buffer is Pinned
*
*/
static void StartBufferIO(BufferDesc *buf, bool forInput)
{
Assert(!InProgressBuf);
Assert(!(buf->flags & BM_IO_IN_PROGRESS));
buf->flags |= BM_IO_IN_PROGRESS;
#ifdef HAS_TEST_AND_SET
Assert(S_LOCK_FREE(&(buf->io_in_progress_lock)))
S_LOCK(&(buf->io_in_progress_lock));
#endif /* HAS_TEST_AND_SET */
InProgressBuf = buf;
IsForInput = forInput;
}
/*
* Function:TerminateBufferIO
* (Assumptions)
* My process is executing IO for the buffer
* BufMgrLock is held
* The buffer is Pinned
*
*/
static void TerminateBufferIO(BufferDesc *buf)
{
Assert(buf == InProgressBuf);
#ifdef HAS_TEST_AND_SET
S_UNLOCK(&(buf->io_in_progress_lock));
#else
if (buf->refcount > 1)
SignalIO(buf);
#endif /* HAS_TEST_AND_SET */
InProgressBuf = (BufferDesc *)0;
}
/*
* Function:ContinueBufferIO
* (Assumptions)
* My process is executing IO for the buffer
* BufMgrLock is held
* The buffer is Pinned
*
*/
static void ContinueBufferIO(BufferDesc *buf, bool forInput)
{
Assert(buf == InProgressBuf);
Assert(buf->flags & BM_IO_IN_PROGRESS);
IsForInput = forInput;
}
extern void InitBufferIO(void)
{
InProgressBuf = (BufferDesc *)0;
}
/*
* This function is called from ProcReleaseSpins().
* BufMgrLock isn't held when this function is called.
* BM_IO_ERROR is always set. If BM_IO_ERROR was already
* set in case of output,this routine would kill all
* backends and reset postmaster.
*/
extern void AbortBufferIO(void)
{
BufferDesc *buf = InProgressBuf;
if (buf)
{
Assert(buf->flags & BM_IO_IN_PROGRESS);
SpinAcquire(BufMgrLock);
if (IsForInput)
{
Assert(!(buf->flags & BM_DIRTY));
}
else
{
Assert(!(buf->flags & BM_DIRTY));
/* Assert(!(buf->flags & BM_IO_ERROR)); */
if (buf->flags & BM_IO_ERROR)
{
elog(NOTICE, "!!! write error seems permanent !!!");
elog(NOTICE, "!!! now kill all backends and reset postmaster !!!");
proc_exit(255);
}
buf->flags |= BM_DIRTY;
}
buf->flags |= BM_IO_ERROR;
TerminateBufferIO(buf);
buf->flags &= ~BM_IO_IN_PROGRESS;
SpinRelease(BufMgrLock);
}
}